Process for the preparation of alkylimidazolidone (meth)acrylates

ABSTRACT

The invention relates to a process for the preparation of alkylimidazolidone (meth)acrylates, generally expressed as compound (I):  
                 
 
     that are prepared by reacting at least one (meth)acrylate of formula (II):  
                 
 
     with a heterocyclic alcohol of formula (III):  
                 
 
     in the presence of a catalyst comprising at least one compound (a) which is a chelate formed of lithium and of a 1,3-dicarbonyl compound. The invention also relates to a composition comprising compound (I) in solution in (meth)acrylate (II). Finally, the invention involves the use of the abovementioned composition in the preparation of polymers that can be used as coatings and adhesives, in the treatment of paper and of textiles, as agent for leather treatment and in the production of paints with high wet adhesion characteristics.

FIELD OF THE INVENTION

[0001] The present invention relates to a process for the preparation ofalkylimidazolidone (meth)acrylates.

BACKGROUND

[0002] Alkylimidazolidone acrylates and methacrylates are known fortheir role in the constitution of polymers which can be used as coatingsand adhesives, in the treatment of paper and of textiles, for their useas agents for leather treatment and in the production of emulsionpaints.

[0003] European patent application No. 236 994 relates to thepreparation of esters of (meth)acrylic acid by reacting an alkyl(meth)acrylate with a heterocyclic alcohol in the presence of a catalystthat is a titanium alkoxide or a titanium, zirconium, iron or zincchelate, combined with a 1,3-dicarbonyl compound, which may be a metalchelate of a 1,3-diketone, in particular an acetylacetonate.

[0004] Such a catalyst has the major disadvantage of generatingintensely coloured products.

[0005] European patent application No. 433 135 relates to a process forthe synthesis of an alkylimidazoline (meth)acrylate, in which an alkyl(meth)acrylate is reacted with a heterocyclic alcohol in the presence ofa catalyst chosen from dialkyl tin oxides, dialkyl tin dialkoxides anddialkyl tin diesters.

[0006] Such a catalyst requires high reaction temperatures and oftencauses violent polymerizations with formation of a very hard expandedpolymer.

[0007] European patent application No. 453 638 also relates to thesynthesis of an alkylimidazoline (meth)acrylate in the presence ofdialkyl tin oxide.

[0008] The subject of European patent application No. 571 851 is aprocess for the preparation of alkylimidazoline (meth)acrylate, bytransesterification of an alkyl (meth)acrylate by means of aheterocyclic alcohol, in the presence of a catalytic system which is acombination of a catalyst based on lithium, for example in oxide,alkoxide, acetate, chloride or bromide form, and a catalyst based oncalcium, such as calcium oxide.

[0009] European patent application No. 619 309 relates to thepreparation of alkylimidazoline (meth)acrylate by reacting an alkyl(meth)acrylate with a heterocyclic alcohol in the presence of a catalystchosen from the chelates of calcium with 1,3-dicarbonyl compounds, suchas calcium acetylacetonate. The products obtained by the processdescribed in that document has an excessively strong colour.

[0010] Finally, European patent application No. 902 017 mentions the useof a catalyst that may be lithium, lithium carbonate or lithiumhydroxide in the preparation of a monomer from, in particular,hydroxyethyloxazolidine and methyl methacrylate.

[0011] However, the use of such catalytic systems does not make itpossible to simultaneously achieve the following main objectives:

[0012] a high conversion of the heterocyclic alcohol;

[0013] a low content of by-products;

[0014] a high kinetic;

[0015] a low thermal level; and

[0016] a faint colouring of the final product.

[0017] The subject of the invention is a process for the preparation ofalkylimidazoline (meth)acrylate, a process which makes it possible toachieve the objectives mentioned above.

[0018] Specifically, the subject of the invention is a process for thepreparation of compound (I):

[0019] wherein:

[0020] R¹ is a hydrogen atom or a methyl group; and

[0021] A and B represent, independently of each other, a straight- orbranched-chain alkylene group having from 2 to 5 carbon atoms;

[0022] by reacting at least one (meth)acrylate (II):

[0023]  wherein:

[0024] R¹ has the abovementioned meaning; and

[0025] R² is a straight- or branched-chain alkyl group having from 1 to4 carbon atoms;

[0026] with a heterocyclic alcohol (III):

[0027]  wherein A and B have the abovementioned meanings;

[0028] in the presence of a catalyst comprising at least one compound(a) which is a chelate formed of lithium and of a 1,3-dicarbonylcompound.

[0029] The subject of the invention is also a composition comprisingcompound (I) obtained by the process according to the invention insolution in (meth)acrylate (II).

[0030] Finally, the subject of the invention is also the use of theabove-mentioned composition in the preparation of polymers that can beused as coatings and adhesives, in the treatment of paper and oftextiles, as agent for leather treatment and in the production of paintswith high wet adhesion characteristics.

DETAILED DESCRIPTION

[0031] The preparation process according to the invention, as has beendescribed above, makes use of a catalyst comprising at least onecompound (a) which is a chelate formed of lithium and of a1,3-dicarbonyl compound.

[0032] Examples of 1,3-dicarbonyl compounds include but are not limitedto the following:

[0033] a β-ketonic acid ester, such as acetylacetic ester;

[0034] a 1,3-diketone, such as acetylacetone, 3-methylacetylacetone,benzoylacetone, dibenzoylmethane, 2,4-hexanedione, 3,5-heptanedione,3-phenylacetylacetone, 4,4,4-trifluoro-1-phenyl-1,3-butanedione,2,2,6,6-tetramethyl-3,5-heptanedione,1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione and1,1,1-trifluoro-2,4-pentanedione.

[0035] Lithium acetylacetonate is most particularly preferred ascompound (α).

[0036] Examples of reagent (II) include, but are not limited to, methyl,ethyl, n-propyl, isopropyl, n-butyl and isobutyl acrylates andmethacrylates.

[0037] Preferably, reagent (II) is methyl methacrylate or acrylate.

[0038] An example of reagent (III) is1-(2-hydroxyethyl)imidazolidyl-2-one, among others.

[0039] The quantity of compound (a) used for carrying out the processaccording to the invention is usually defined relative to the quantityof heterocyclic alcohol.

[0040] Thus, the molar ratio of compound (a) to the heterocyclic alcohol(III) is generally between 0.05 and 0.3 percent, and preferably between0.05 and 0.15 percent.

[0041] In an advantageous variant of the process according to theinvention, compound (a) is not used alone as catalyst, but rather in theform of a mixture together with a second compound (b). Computer (b) maybe chosen from magnesium alkoxides, sodium alkoxides, calcium alkoxides,calcium acetylacetonate, calcium oxide and calcium hydroxide.

[0042] As alkoxides, examples include methoxides, ethoxides, propoxides,isopropoxides, butoxides and isobutoxides.

[0043] With regard to the quantity of compound (b), it may be less thanthat of compound (a).

[0044] Typically, the quantity of compound (b) is chosen such that themolar ratio of compound (b) to the heterocyclic alcohol (III) is between0.01 and 0.1 percent, and preferably between 0.01 and 0.05 percent.

[0045] The reaction between reagent (II) and reagent (III) is generallycarried out in the presence of an excess of either of these reagents.

[0046] It is, however, preferable to use more of reagent (II) thanreagent (III).

[0047] Thus, it is desirable that the molar ratio of the (meth)acrylate(III) to the heterocyclic alcohol (III) is greater than 1, preferablybetween 1.1 and 7, more preferably between 2 and 5.

[0048] In this manner, a composition comprising a solution of compound(I) in (meth)acrylate (II) is obtained as the product of the reaction,for example:

[0049] a solution of 1-ethylimidazolidyl-2-one acrylate in methylacrylate; or alternatively

[0050] a solution of 1-ethylimidazolidyl-2-one methacrylate in methylmethacrylate.

[0051] Such a composition, which has a colour of less than 100 APHA, maybe advantageously used directly in certain applications such as themanufacture of paints with high wet adhesion characteristics, thetreatment of leather or the manufacture of coatings.

[0052] The process according to the invention may be carried out in thepresence of one or more polymerization inhibitors, which may be chosenfrom phenothiazine, hydroquinone, the monomethyl ether of hydroquinone,di-tert-butyl-para-cresol, para-phenylenediamine, TEMPO(2,2,6,6-tetramethyl-1-piperidinyloxy) and di-tert-butylcatechol.

[0053] These compounds may be optionally combined with metal chelatorssuch as EDTA, oxalic acid or the products marketed under the trademarkVERSENEX.

[0054] The content of polymerization inhibitor is generally between 0.05and 0.5%, this percentage being expressed as weight of inhibitor (towhich the weight of the associated chelator(s) is added whereappropriate) relative to the weight of heterocyclic alcohol (III).

[0055] Regarding the operating conditions, the process is usuallycarried out at a temperature of between 70 and 120° C., and preferablybetween 85 and 100° C., in liquid medium.

[0056] The pressure is in general at most equal to 1 bar; it istypically between 0.3 and 1 bar.

[0057] It is advantageous to carry out the reaction with bubbling air.

[0058] The duration of the reaction depends on the operating conditionsand the activity of the catalyst. It is generally between 6 and 11hours.

[0059] The reaction is desirably carried out in an anhydrous medium inorder to avoid the deactivation of the catalysts.

[0060] The water present in the reagents is preferably removed bydistillation in the form of an azeotrope of (meth)acrylate (II) andwater.

[0061] The procedure may be briefly described as follows.

[0062] A mixture of the reagents (II) and (III) and of the inhibitor(s)is heated under reflux, while adjusting the pressure in the installationso that the temperature in the reactor is maintained between 85 and 100°C.

[0063] The column is stabilized by introducing one or morepolymerization inhibitors at the top of the column, in the reflux.

[0064] The water present in reagents (II) and (III) and the inhibitor isremoved by distillation in the form of an azeotrope with the(meth)acrylate (II).

[0065] The catalyst(s) is(are) then introduced.

[0066] The reaction is carried out with generation of the alcohol R²OH,which is removed by formation of an azeotrope with the (meth)acrylate(II), in order to displace the equilibrium of the transesterificationreaction.

[0067] Thus, the equilibrium of the transesterification reaction isdisplaced in the direction of the formation of compound (I).

[0068] Throughout the duration of the reaction, the pressure is adjustedin order to maintain the temperature inside the reactor between 85 and100° C.

[0069] If necessary, catalyst(s) is(are) supplied during the reaction.

[0070] When no further alcohol R²OH is formed, the reaction may beconsidered to be complete.

[0071] The crude product obtained is then cooled and extracted from thereactor. It is generally in the form of a clear and very slightlycoloured liquid (colour less than 100 APHA).

[0072] Any excess of (meth)acrylate may then be removed by evaporation(so-called stripping operation), so as to isolate compound (I) from thereaction medium, generally in the solid state: thus, the1-ethylimidazolidyl-2-one acrylate is a white crystalline solid having amelting point equal to 43° C., which is soluble in the cold state inketones, alcohols, aromatic hydrocarbons and water, insoluble in thecold state in saturated hydrocarbons and which precipitates at 0° C.from ethyl acrylate. 1-Ethylimidazolidyl-2-one methacrylate is a whitecrystalline solid having a melting point equal to 47° C., possessing thesame solubility properties as the preceding compound. At the end of thestripping operation, the crystalline solid product may in addition bepurified by washing with a light alcohol such as methanol and/or with apetroleum ether, followed by filtration and drying.

[0073] The isolation of compound (I) may also be carried out by partialstripping of the (meth)acrylate (II), followed by crystallization at asufficiently low temperature (preferably of less than or equal to 0° C.)and for a sufficiently long period (which may be up to 15 hours), andthen filtration followed by the purification steps described above.

[0074] Finally, another method for isolating compound (I) from thesolution containing it consists of carrying out an extraction withwater, followed by decantation, stripping of the (meth)acrylate and thepurification steps described above.

EXAMPLES

[0075] The following examples illustrate the present invention without,however, limiting the scope thereof.

[0076] The following abbreviations are used therein: MMA: methylmethacrylate HEIO: 1-(2-hydroxyethyl)imidazolidyl-2-one EIOM:1-ethylimidazolidyl-2-one methacrylate MEHQ: monomethyl ether ofhydroquinone PTZ: phenothiazine Li(acac): lithium acetylacetonateCa(acac)₂: calcium acetylacetonate DBTO: dibutyltin oxide

Examples 1 to 3

[0077] Into a jacketed 630-litre stainless steel reactor supplied with athermofluid, equipped with a mechanical stirrer and surmounted by adistillation column (diameter 250 mm, height 4 m), filled with a PALLpacking and surmounted by a reflux head, are introduced:

[0078] 150 kg of HEIO;

[0079] 461 kg of MMA; and

[0080] 0.2 kg of PTZ (polymerization inhibitor).

[0081] The column is stabilized by introducing into the reflux asolution of MEHQ at 0.1% by weight in MMA.

[0082] The reaction mixture is dried by azeotropic distillation of thewater contained in the reagents (the azeotrope being formed between theMMA and the water) under a pressure of 400 mmHg (the temperature at thetop of the column is 77° C.).

[0083] When the drying step is complete, the catalyst(s) is(are)introduced and additional methyl methacrylate is added in order tomaintain the MMA/EIOM molar ratio at its initial value of 4/1.

[0084] Throughout the duration of the reaction, the pressure is adjustedin order to maintain the temperature in the reactor at 85° C.

[0085] The methanol formed by the reaction is removed in the form of anazeotrope with the MMA.

[0086] The reaction is complete when the temperature at the top of thecolumn no longer falls towards that of the azeotrope, in total reflux,at the operating pressure.

[0087] The crude product is then cooled and analysed by HPLC.

[0088] The colour of the crude product is an important factor. It shouldbe as faint as possible.

[0089] Examples 1 to 3 of the following Table A were all performed underthe above conditions, by varying the nature of the catalyst(s). Example2, outside the scope of the invention, was performed for the sake ofcomparisons: the catalyst does not contain compound (a).

[0090] It is therefore seen that the EIOM yields are comparable forExamples 1 to 3. Nevertheless, the catalyst of Comparative Example 2gives a final product having a strong colour. TABLE A Exam- Catalyst andmol % Duration of the Colour of the crude ple relative to the HEIOreaction in hours Product in APHA 1 Li(acac): 0.15 10 41 2 Ca(acac)₂:0.15 10 100 (comp.) 3 Li(acac) and Ca(acac)₂ 8 74 0.15 and 0.10(respectively) Composition of the crude product Exam- (% by mass) pleMMA % HEIO % EIOM % 1 57.8 1.2 33.3 2 58.7 1.4 35.7 (comp.) 3 58.4 1.134.5

Examples 4 to 9

[0091] Trials were carried out in a small jacketed glass reactor whichis mechanically stirred and surmounted by a glass distillation column,containing a “multiknit” packing (efficiency of 8 theoretical plates)and provided with a reflux head.

[0092] The general conditions are identical to those of Examples 1 to 3,the only exception being the MMA/HEIO molar ratio which is now 3.5/1(instead of 4/1 previously).

[0093] Examples 5, 6 and 7, outside the scope of the invention, wereperformed for the sake of comparison: their catalysts do not containcompound (a).

[0094] The results are presented in the following Table B.

[0095] It is therefore seen that the catalysts of the ComparativeExamples 5, 6 and 7 free of compound (a) give a strongly coloured finalproduct. TABLE B Exam- Catalyst and mol % Duration of the Colour of thecrude ple relative to the HEIO reaction in hours Product in APHA 4Li(acac): 0.2 7.5 50 5 DBTO: 1.3 15 150 (comp) 6 Zr(acac)₂ 8 120 (comp.)0.2 7 Ca(acac)₂: 0.2 6 110 (comp.) 8 Li(acac) and Ca(acac)₂ 6.5 70 0.2and 0.1 (respectively) 9 Li(acac) and 7 80 Mg(OEt)₂ 0.2 and 0.1(respectively) Composition of the crude product Exam- (% by mass) pleMMA % HEIO % EIOM % 4 50.2 1.0 40.8 5 52.9 0.6 49.6 (comp.) 6 51.5 0.344.5 (comp.) 7 51.8 1.7 38.7 (comp.) 8 50.7 1.2 40.2 9 50.2 1.8 39.2

What is claimed is:
 1. A process for the preparation of compound (I):

wherein: R¹ is a hydrogen atom or a methyl group; and A and B represent,independently of each other, a straight- or branched-chain alkylenegroup having from 2 to 5 carbon atoms; by reacting at least one(meth)acrylate of formula (II):

 wherein: R¹ has the abovementioned meaning; and R² is a straight- orbranched-chain alkyl group having from 1 to 4 carbon atoms; with aheterocyclic alcohol of formula (III):

 wherein A and B have the abovementioned meanings; in the presence of acatalyst comprising at least one compound (a) which is a chelate formedof lithium and of a 1,3-dicarbonyl compound.
 2. The process according toclaim 1, wherein the 1,3-dicarbonyl compound is: a β-ketonic acid ester,such as acetylacetic ester; or a 1,3-diketone, such as acetylacetone,3-methylacetylacetone, benzoylacetone, dibenzoylmethane,2,4-hexanedione, 3,5-heptanedione, 3-phenylacetylacetone,4,4,4-trifluoro-1-phenyl-1,3-butanedione,2,2,6,6-tetramethyl-3,5-heptanedione,1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione and1,1,1-trifluoro-2,4-pentanedione.
 3. The process according to claim 2,wherein compound (a) is lithium acetylacetonate.
 4. The processaccording to claim 1, wherein said (meth)acrylate of formula (II) ismethyl acrylate or methacrylate, and said heterocyclic alcohol offormula (III) is 1-(2-hydroxyethyl)imidazolidyl-2-one.
 5. The processaccording to claim 1, wherein the molar ratio of compound (a) to theheterocyclic alcohol of formula (III) is between 0.05 and 0.3%, orbetween 0.05 and 0.15%.
 6. The process according to claim 1, wherein thecatalyst further comprises at least one compound (b) chosen from thegroup consisting of magnesium alkoxide, sodium alkoxide, calciumalkoxide, calcium acetylacetonate, calcium oxide and calcium hydroxide.7. The process according to claim 3, wherein the catalyst furthercomprises at least one compound (b) chosen from the group consisting ofmagnesium alkoxides, sodium alkoxides, calcium alkoxides, calciumacetylacetonate, calcium oxide and calcium hydroxide.
 8. The processaccording to claim 6, wherein the molar ratio of compound (b) to theheterocyclic alcohol of formula (III) is between 0.01 and 0.1%, orbetween 0.01 and 0.05%.
 9. The process according to claim 8, in whichthe molar ratio of compound (a) to theheterocyclic alcohol of formula(III) is between 0.05 and 0.3%, or between 0.05 and 0.15%.
 10. Theprocess according to claim 1, wherein the process is carried out in thepresence of at least one polymerization inhibitor selected from thegroup consisting of phenothiazine, hydroquinone, the monomethyl ether ofhydroquinone, di-tert-butyl-para-cresol, para-phenylenediamine, TEMPO,di-tert-butylcatechol and at least one of the preceding enumeratedpolymerization inhibitors combined with a metal chelator.
 11. Theprocess according to claim 10, wherein the content of polymerizationinhibitor is between 0.05 and 0.5% by weight relative to the weight ofheterocyclic alcohol of formula (III).
 12. The process according toclaim 1, wherein the process is carried out in an anhydrous medium. 13.The process according to claim 1, wherein the process is carried out ata temperature of between 70 and 120° C. or between 85 and 100° C. 14.The process according to claim 1, wherein the process is carried out ata pressure of between 0.3 and 1 bar.
 15. The process according to claim14, wherein the process is carried out with bubbling air.
 16. Theprocess according to claim 1, wherein the process is carried out in thepresence of an excess of the (meth)acrylate of formula (II) or an excessof the heterocyclic alcohol of formula (III).
 17. The process accordingto claim 16, in which the molar ratio of the (meth)acrylate of formula(II) to the heterocyclic alcohol of formula (III) is greater than 1,preferably between 1.1 and 7, in particular between 2 and
 5. 18. Acomposition comprising a compound (I):

wherein: R¹ is a hydrogen atom or a methyl group; and A and B represent,independently of each other, a straight- or branched-chain alkylenegroup having from 2 to 5 carbon atoms; prepared by reacting at least one(meth)acrylate of formula (II):

 wherein: R¹ has the abovementioned meaning; and R² is a straight- orbranched-chain alkyl group having from 1 to 4 carbon atoms; with aheterocyclic alcohol of formula (III):

 wherein A and B have the abovementioned meanings; in solution in(meth)acrylate of formula (II) in the presence of a catalyst comprisingat least one compound (a) which is a chelate formed of lithium and of a1,3-dicarbonyl compound.
 19. The composition according to claim 18, thecolour of which is less than 100 APHA.
 20. The use of a compositioncomprising a compound (I):

wherein: R¹ is a hydrogen atom or a methyl group; and A and B represent,independently of each other, a straight- or branched-chain alkylenegroup having from 2 to 5 carbon atoms; in the preparation of polymerswhich can be used as coatings and adhesives, in the treatment of paperand of textiles, as agent for leather treatment and in the production ofpaints with high wet adhesion characteristics; wherein said compound offormula (1) is prepared by reacting at least one (meth)acrylate offormula (II):

 wherein: R¹ has the abovementioned meaning; and R² is a straight- orbranched-chain alkyl group having from 1 to 4 carbon atoms; with ahheterocyclic alcohol of formula (III):

 wherein A and B have the abovementioned meanings; in the presence of acatalyst comprising at least one compound (a) which is a chelate formedof lithium and of a 1,3-dicarbonyl compound.